The present invention relates in general to glass grinding machines and in particular to an apparatus for supporting and positioning a planar glass workpiece so as to permit the outer peripheral edge thereof to be ground in accordance with a predetermined pattern.
In the manufacture of certain glass articles, such as vehicle windshields and the like, a planar glass workpiece is initially formed and cut in a shape which closely approximates the ultimate shape of the final article. Following such initial formation, a grinding operation is usually performed on the outer peripheral edge of the workpiece in order to insure that the dimensions thereof conform to predetermined tolerances. The grinding operation causes a small amount of glass to be removed from the outer peripheral edge of the workpiece in order to precisely define the shape of its perimeter. Since the workpiece is frequently incorporated into an assembly in which the outer peripheral edge cooperates with a fluid tight seal, it is very important that the dimensions thereof be formed closely in accordance with the predetermined tolerances.
In order to accomplish this grinding operation, a grinding apparatus has been utilized in the past to support and position the glass workpiece, as well as to grind the outer peripheral edge thereof. Such a grinding apparatus included a supporting platform having one or more locators movably connected thereto. The locators were initially positioned manually in a predetermined position relative to the supporting platform by means of a template or other mechanical device. The positions of the locators defined points which, when abutted by the outer peripheral edge of the glass workpiece, properly positioned such workpiece relative to the supporting platform. Once the locators were properly positioned, the glass workpiece was laid upon the top of the supporting platform and manually pushed in sliding fashion until its outer peripheral edge abutted each of the locators. Then, the workpiece was clamped to the table, and the locators were retracted to non-engaging positions. The table was next rotated relative to an edge grinder, which was also movably connected to the supporting platform. As the edge of the workpiece moved by the edge grinder, material was removed therefrom in accordance with predetermined pattern.
The manual positioning of the locators was a slow and inefficient process in the initial set up of the grinding apparatus. Such inefficiencies were compounded if the grinding apparatus was utilized to grind the edges of a number of differently sized workpieces. Each differently sized glass workpiece required the locators to be manually repositioned. Accordingly, it would be desirable to provide a grinding apparatus which permits the locators to be automatically repositioned in a quick and easy manner for differently sized glass workpieces. At the same time, such a grinding apparatus must also be able to perform the grinding operation rapidly and accurately, thus requiring the planar glass workpieces to be consistently and accurately positioned at the same relative location within the glass grinding apparatus.